Coating for steam iron flash boiler



` Nov. 23, 1965 F. A. MARTIN 3,218,741

COATING FOR STEAM IRON FLASH BOILER Filed Sept. 3. 1963 United States Patent O 3,218,741 COATING FOR STEAM IRON FLASH BOILER Frank A. Martin, Akron, Ohio, assigner to The Hoover Company, North Canton, Ohio, a corporation of Ghio Filed Sept. 3, 1963, Ser. No. 305,973 7 Claims. (Cl. 3S-77) The present invention relates to coatings for the flash boiler of steam irons and to the method of applying such coatings.

In steam irons of the ash boiler type the water is fed drop by drop onto a hot spot on the sole plate, usually depressed below the top surface of the sole plate, and which constitutes the flash boiler.

If no means is provided to prevent it, the drops of water will roll about over the surface without being evaporated, and be ejected or spit onto the material being ironed in the form of water droplets which stains the material.

In the past the ash boiler has been coated with a hydrophilic material such as sodium silicate which prevents the spitting but eventually wears away.

According to the present invention the ash boiler is coated with mica akes partially embedded in the metal of the sole plate and held in place to some extent by a binder.

The coating is applied to the die before the sole plate is cast and transferred to the sole plate during the casting operation thus doing away with a separate cooling operation after the sole plate is formed, which operation is expensive and time consuming.

According to the present invention a water suspansion of a mixture of the mica and binder is sprayed onto the hot die (which is maintained at about 600 F.), at that point on the die which forms the ash boiler, the die closes and the castings immediately form.

The water forming the suspension is immediately evaporated, and the mica and binder desposited on the die as a coatng. As the casting is formed, the coating is transferred to the casting and the mica partially embedded in the metal of the casting.

The primary purpose of the binder is to form the Water suspension for the mica. The binder used is a white uty powder consisting mainly of colloidal alumina (A1203) sold under the trade name of Baymalf Other objects and advantages of the present invention will become apparent as the descr-iption proceeds when taken in connection with the accompanying drawing in which:

FIG. 1 is a perspective view showing the die being coated.

FIG. 2 is a perspective v-iew of the top of a sole plate; and

FIG. 3 is an enlarged cross-sectional view of the bottom of the Hash boiler taken on l-ine 3 3 of FIG. 2.

The female die has a depressed portion 11 which forms the body 12 of the sole plate, a raised portion 13 which forms the flash boiler 14 connected to a raised portion 15 which forms the steam passages 16. A sprayer 17 of any suitable type is shown in FIG. l applying the suspension to an area limited to the raised portion 13 which forms the flash boiler 14, the coating being shown at 18.

The coating 19 of FIG. 3 was drawn from a microphotograph of a section of the metal of the sole plate,

3,218,741 Patented Nov. 23, 1965 the section being cut through the bottom of the flash boiler.

As shown the tail ends of the mica akes 20 are embedded in the metal of the sole plate and lie in overlapping or shingle like formation.

While in FIG. 3 the mica Hakes 20 are shown in a regular arrangement the micro-photograph shows them in more of a haphazard arrangement but the general arrangement is clear.

A silica layer 21 overlies the flakes 20 with the ilakes projecting above the surface of the silica as shown.

The Baymal and mica crystals are placed in a container, Water added and the container agitated to form a suspension.

The sprayer 17 is of the air jet type of known construction. The liquid suspension is led to the sprayer 17 by tube 22 and air by tube 23.

The die 10 is maintained at about 600 F. and as the spray is applied the water is immediately evaporated leaving the coating 18 of mica and alumina mostly positioned on top of the ra-ised portion 13 of the die. Of course the coating is not limited to that area but that is the area which it is desired to coat.

The die is immediately closed and the sole plate 12 cast. The coating 1S is transferred to the bottom 14 in the form of coating 19 in which the flakes 20 are arranged in shingle or ish scale like formation with their tail ends embedded in the metal of the sole plate and with their upper ends projecting above the layer 21 of alumina to form a roughened surface.

While I have shown and described but a single embodiment of my invention it is to be understood that that embodiment is to be taken as illustrative only and not in a limiting sense. I do not wish to be limited to the specific structure and method shown and described but wish to include all equivalent variations thereof except as limited by the scope of the claims.

I claim:

1. A sole plate for a steam iron, a flash boiler formed on said sole plate and a coating embedded in the surface of said llash boiler including mica Hakes and an alumina binder for said mica llakes.

2. A sole plate for a steam iron, a flash boiler formed on the upper side of said sole plate and a coating on the surface of said dash boiler including mica akes and alumina, said mica Hakes being arrange-d in overlapping relationship with the tails thereof embedded in the metal of said sole plate and the upper ends exposed through said alumina.

3. The method of coating an aluminum casting comprising, maintaining a forming die at an elevated temperature, spraying said die with a coating material prepared in a water suspension whereby said water is evaporated and said coating material is deposited on said die, closing said die and immediately forming said casting whereby said coating material is transferred from said die to said casting.

4. The method according to claim 3 in which said coating material is a mixture of mica akes and alumina.

5. The method of coating the ash boiler of a steam iron comprising, maintaining a casting die at an elevated temperature, forming a water suspension of a mixture of mica akes and alumina, spraying that portion of said die which forms the flash boiler with said suspension whereby the water is evaporated and the mixture of mica 3 4 crystals and alumina is deposited on said die as a coat- References Cited by the Examiner ing and casting said sole plate with said coated die Where- UNITED STATES PATENTS by said coating is transferred to said casting as a coating for the Hash boiler of said 50161112116, 2,055,507 9/ 1936 Shirley 117-160 6. The method according to claim 5 in which said 5 2,075,388 3/197 De Cloud 117-160 en s thereof embe e 1n e me a of sal so e p a e 3,101,561 8/1963 Albrecht et al' 38-77 7. The method according to claim 6 in which said alumina forms a coating over said mica akes with the upper edges of said akes projecting above said coating. l0 JORDAN FRANKLIN Pnmary Examiner' 

1. A SOLE PLATE FOR A STEAM IRON, A FLASH BOILER FORMED ON SAID SOLE PLATE AND A COATING EMBEDDED IN THE SURFACE OF SAID FLASH BOILER INCLUDING MICA FLAKES AND AN ALUMINA BINDER FOR SAID MICA FLAKES. 